Reaction switch



Feb. 4, 1958 R. G. TOWLE 2,822,436

REACTION SWITCH Filed July 20. 1954 myzmoa R0661"; GTow/e ATTO R N EYUnited States Patent REACTION SWITCH Robert G. Towle, New City, N. Y.,assignor to Specialties Development Corporation, Belleville, N. J., acorporation of New Jersey Application July 20, 1954, Serial No. 444,4853 Claims. (Cl. ZOO-61.41)

This invention relates to electrical circuit makers, and, moreparticularly to switches which are operable by excessive movement of amounted structure.

Heretofore, it has been proposed to provide aircraft with systems whichare automatically operable in the event of a crash to prevent explosionsor the breaking out of fire. In such systems, it is necessary thatinitiating means be able to sense a crash as distinguished from otherless violent occurrences such as storms and the like, normal relativemovement of parts within predetermined limits, such as is occasioned byvibrations, for example, as well as from malfunction of components inthe system itself. Such systems may therefore be operated by theactuation of a plurality of switches simultaneously, each of whichresponds to a different condition which has been found to occur during acrash.

Careful study of crashes revealed that explosion or fire often resultwhen, due to the force of the impact, an engine is torn loose from itsmount severing fuel and oil lines and permitting the contents thereof tospill and contact hot engine parts such as the cylinder block, exhaustmanifold and the like.

Accordingly, it is an object of the present invention to provide aswitch mechanism which is adapted to control an electrical circuit inthe event that an engine, for example, is caused to move with respect tothe aircraft frame in excess of the movement due to normal vibration andtorque.

It is another object to provide such apparatus including an initiatingmember abutting the engine structure capable of reacting to excessivemovement thereof such as might occur in the event of a crash.

It is another object to provide such apparatus wherein excessivemovement of the engine structure in any direction will effect actuationof the circuit controlling means.

It is a further object to provide such apparatus which is reliable andefficient in operation, is easily installed, cannot get out ofadjustment, is light in weight, requires little maintenance, is freefrom damage due to moisture or dust and has a long shelf life.

Other and further objects of the invention will be obvious upon anunderstanding of the illustrative embodiment about to be described, orwill be indicated in the appended claims, and various advantages notreferred to herein will occur to one skilled in the art upon employmentof the invention in practice.

In accordance with the present invention, the foregoing objects aregenerally accomplished by providing, in combination with craft havingstructure arranged for movement within predetermined limits, a rodhaving a surface abutting the structure and being movable from itsnormal position in either of its longitudinal directions, spring meansfor urging the rod towards the structure, actuating means and an elementmovable with the rod for effecting operation of the actuating means uponmovement of the structure beyond the limits.

A preferred embodiment of the invention has been chosen for purposes ofillustration and description, and

is shown in the accompaning drawing, forming a part of thespecification, wherein the single figure is a side elevational view,partly in section, of apparatus in accordance with the presentinvention.

Referring to the drawing in detail, there is shown a frame or casing 10supporting a conventional switch 11 and formed with a pair of oppositeapertures 12 and 14 in the ends thereof and with a sleeve portion 13surrounding the aperture 14 and extending outwardly thereof. Slidebearings 15 and 16 are mounted in the respective apertures 12 and 14, arod 17 is slidably mounted in the bearing 15 and has an inner end withinthe casing and an outer end projecting outwardly therefrom, an elongateelement 19 connected to the inner end of the rod 17 for movementtherewith is slidably mounted in the other bearing 16, and a helicalcompression spring 20 is arranged for urging the outer end of the rod 17outwardly of the bearing 15.

The switch 11 is provided with an actuating plunger 21 and an operatingarm 22 formed preferably of spring steel, secured at one end to theswitch body and positioned over the plunger at its other end. A roller24 is mounted at the free end of the arm and is normally urged by thespring action thereof in a direction away from the plunger 21. Theterminals of the switch are connected to an electrical connector 25 inthe casing in the usual manner.

The bearing 15 is formed with an elongate sleeve portion 26 throughwhich the rod 17 extends, and a flanged collar 27 is secured to the rodadjacent its outer end for movement therewith. The spring 20 fits overthe sleeve 26 and bears against the flanged collar 27 at one end andagainst the bearing 15 at the other end to urge the rod 17 to the left,as viewed. The inner end of the rod, disposed within the casing, isscrew threaded and is formed with a flat zone 29 extendinglongitudinally to a point within the bearing 15. A pin 30 mounted in thebearing 15 extends through the bearing opening and abuts the flat zone29 of the rod for a purpose to be described hereinafter.

The element 19, slidably mounted in the bearing 16, is generallycylindrical in contour and is formed with a section 31 of reduceddiameter having frusto-conical cam faces 32 and 34 at the respectiveends for actuating the switch as described hereinafter. The inner end ofthe element 19 is provided with an internally threaded longitudinal bore35 for securing the inner end of the rod 17 for movement therewith. T heelement 19 is provided with a diametric slot 36 at its free end and witha circumferential groove 37 adjacent that end. A pin 39 is mounted inthe element 19 and extends radially outwardly therefrom at each endthereof, and is disposed within a pair of diametrically opposite slots40 in the end of the sleeve portion 13.

To mount the device for actuating the switch 11 upon movement of anaircraft engine, for example, in excess of the normal movement due tovibration and torque, the casing 10 may be secured to the aircraft framestructure in such a manner that the longitudinal axis of the rod isparallel to the longitudinal axis of the engine and that the free end ofthe rod 17 abuts a surface S on or attached to the engine for thatpurpose. The dimensions of such a surface will depend upon the maximumallowable torque reaction of the particular engine involved. Forexample, if the maximum torque reaction of an engine is 4 clockwise and1 counterclockwise, this vertical surface is so dimensioned thatmovement in excess of maximum torque reaction will move the surface outof abutment with the end of the rod 17.

The position of the section 31 of reduced diameter of the element 19with respect to the roller 24 is adjusted by manually urging the rod 17in a direction against the action of the spring 20 until the pin 39 inthe element.

19 is moved out of the slots 40. The element 19 is then rotated by theaction of a suitable tool in the slot 36 until, upon release of the rod17, the pin 39 moves back into the slots 40 and the groove 37 lines upwith the end of the sleeve portion 13. Aligning the groove and thesleeve portion automatically locates the center of the section 31 inabutting relation with the roller 24, thus permitting adjustment withoutthe necessity of opening the casing.

After the mechanism has been properly adjusted, the pin 30 bearingagainst the fiat zone 29 and the pin 39 extending into the slots 40prevent rotation of the rod 17 and the element 19, respectively, so thatthe mechanism cannot get out of adjustment as a result of vibration, forexample, and also prevent excessive longitudinal movement of the rod andthe element.

The dimensions of the section 31 of reduced diameter including the camfaces 32 and 34 will be determined by the al'owable maximum longitudinalvibrational excursion of the particular engine involved. For example,one quarter of an inch may be the maximum longitudinal vibrationalexcursion allowed for the aforementioned engine, wherefore, when used inconnection with that engine, the section 31 is dimensioned to effectactuation of the switch upon longitudinal movement of the engine througha distance greater than one eighth of an inch from its normal position.

In operation, normal vibration or torque reaction of the engine will notcause or permit suflicient movement of the rod 17 to allow either of thecam faces 32 or 34 to abut the roller 24 to depress the arm 22 andeffect actuation of the switch through the plunger 21. However, in theevent of excessive movement of the engine with respect to the aircraftframe, due to collision or crash, for example, the rod 17 will be movedin one of its longitudinal directions, either by the engine or thespring depending upon the direction of movement of the engine, until oneof the cam faces 32 or 34 abuts and depresses the roller 24 sufiicientlyto effect actuation of the switch 11.

In order to seal the apparatus against moisture and dust, a cap 41,formed to permit movement of the element 19, may be screw threaded tothe sleeve portion 13 and conventional O-rings may be disposed betweenthe sleeve portion and the cap and between the bearing 15 and the rod17. Likewise, the outer end of the rod 17 and the spring may be enclosedby a flexible housing 42 to prevent corrosion or contamination of thespring.

From the foregoing description, it will be seen that the presentinvention provides a switch mechanism adapted to control an electricalcircuit in the event that an engine, for example is caused to move withrespect to its frame in excess of the movement due to normal vibrationand torque, which mechanism is reliable and efficient in operation, iseasily installed, cannot get out of adjustment, is light in weight,requires little maintenance, is free from damage due to moisture or dustand has a long shelf life.

As various changes may be made in the form, construction and arrangementof the parts herein, without departing from the spirit and scope of theinvention and withoutsacrificing any of its advantages, it is to beunderstood that all matter herein is to be interrupted as illustrativeand not in any limiting sense.

I'claim:

:1. A control mechanism of the class described comprising a frame havingaligned apertures in opposite sides thereof, a slide bearing in each ofsaid apertures, switch means supported by said frame having a memberadapted to be actuated, a rod slidably mounted in one of said bearingsand extending through said frame formed with a flat zone extendinglongitudinally from the inner end thereof to a point within saidrod-mounting bearing, a spring retainer at the outer'end of said rod, anelement adjustably connected to the inner end of said rod and slidablymounted in the other of said bearings, said element having anintermediate section of reduced diameter formed with oppositely facingfrusto-conical cam faces at its respective ends for actuating saidswitch means member, a cylindrical helical spring surrounding said rodand extending between said retainer and said frame for urging said rodoutwardly of its bearing, a slot formed in the free end of said elementadapted to be engaged by a tool for adjusting the position of saidelement with respect to said rod and said switch means, a pin projectingradially from said element adjacent the free end thereof, a stop in saidelement-mounting hearing constructed and arranged to receive said pin tolimit the movement of said element, and pin means supported in saidrod-mounting bearing etxending transversely of said rod and abuttingsaid fiat zone thereof to prevent rotation of said rod.

2. A control mechanism of the .class described comprising a frame havingaligned apertures in opposite sides thereof, a slide bearing in each ofsaid apertures, switch means supported by said frame having a memberadapted to be actuated, a rod slidably mounted in one of said bearingsand extending through said frame, a spring retainer at the outer end ofsaid rod, an element adjustably connected to the inner end of said rodand slidably mounted in the other of said bearings, said element havingan intermediate section of reduced diameter formed with oppositelyfacing frusto-conical earn faces at its respective ends for actuatingsaid switch means member, a cylindrical helical spring surrounding saidrod and extending between said retainer and said frame for urging saidrod outwardly of its bearing, a cap secured to said element-mountingbearing for sealing one of said apertures, and a flexible sleeve mountedat one end of said rod-mounting bearing and attached at its other end tothe outer end of said rod to seal the other of said apertures.

3. A control mechanism of the class described comprising a frame havingaligned apertures in opposite sides thereof, a slide bearing in each ofsaid apertures, switch means supported by said frame having a memberadapted to be actuated, a rod slidably mounted in one of said bearingsand extending through said frame, a spring retainer at the outer end ofsaid rod, an element adjustably connected to the inner end of said rodand slidably mounted in the other of said bearings, said element havingan intermediate section formed with cam faces for actuating said switchmeans member, a cylindrical helical spring surrounding said rod andextending between said retainer and said frame for urging said rodoutwardly of its bearing, means formed in the free end of said elementadapted to be engaged for adjusting the position of said element withrespect to said rod and said switch means, stop means on said elementand said elementmounting bearing constructed and arranged to limit themovement of said element, and means on said rod-mounting bearing andsaid rod serving to prevent rotation of said rod.

References Cited in the file of this patent UNITED STATES PATENTS1,629,998 'Field May 24, 1927 2,055,637 Stanley et al Sept. 29, 19362,414,912 Wiatt Jan. 28, 1947 2,581,078 Corfield et al. Jan. 1, 19522,639,337 Framhein May 19, 1953

